Catalytic device for treatment of combustion gases and its method of use, and the catalytic material used in the catalytic device

ABSTRACT

This invention relates to an emission control device containing a catalytic material capable of reducing pollutants in the combustion gases generated from an internal combustion engine, as well as from other combusted solid and liquid fossil fuels such as coal, and is also useful for treating combustion gases generated from the incineration of landfill garbage and tire rubber, among others. The catalytic material of the present invention is highly resistant to deactivation or poisoning from contaminants in the combusted material such as leaded gasoline. The catalytic material predominantly comprises a plagioclase feldspar belonging mainly to the albite-anorthite series and contains small amounts of mica, kaolinite and serpentine, and optionally contains magnetite.

FIELD OF THE INVENTION

The invention relates to a catalytic device for treating combustion gaspollutants with use of a catalytic material derived from an unusualmineral formation of volcanic ash in either its native state or aspreconditioned by magnetic separation. More particularly, the inventionrelates to a catalytic material suitable for a variety of applicationsincluding, but not limited to, (1) treatment of exhaust gases generatedby combustion of fossil fuels, both liquid and solid, and woodmaterials; and (2) treatment of gases generated from incineration oftire rubber and landfill waste; and also (3) scrubbing of steam wellgases. The catalytic material of the present invention displays aremarkable ability to reduce the proportion of exhaust gas pollutantssuch as hydrocarbons, carbon dioxide, carbon monoxide, sulfur dioxide,nitrogen oxides while increasing oxygen output and strongly resistingdeactivation by catalytic poisons.

BACKGROUND OF THE INVENTION

It is well known that the combustion of fossil fuels, e.g., gasoline,generates deleterious automobile exhaust containing carbon monoxide,carbon dioxide, oxides of nitrogen (primarily NO_(x)), water, andnitrogen. The exhaust also can contain a wide variety of hydrocarbonsand also particulates including carbon and oxidized carbon compounds,metal oxides, oil additives, fuel additives, and breakdown products ofthe exhaust system, including the exhaust-control catalysts.

These exhaust products can combine in a large variety of ways in theatmosphere, particularly since the amounts of each material change withoperating conditions and the mechanical state of the vehicle. Thephotochemical reaction between oxides of nitrogen (NO_(x)) andhydrocarbons (HC) that caused the original interest in the automobile asa source of pollution has been investigated extensively.

Due to the now well-appreciated harmful effects of the vehicle emissionpollutants to both health and to the environment in general, everincreasing stringent air quality standards are being imposed onemissions at both a federal and state level.

Also, many commercial operations, industrial is processes or even homeheating systems generate noxious gaseous chemical by-products, theremoval of which must comply with federal or state regulations. Theseregulations may be highly expensive to meet with, if not costprohibitive, using current exhaust gas treatment technology. Therefore,the anticipated benefits of improved environmental quality confers avery high value on any new engineering technology that might be usefulto meet the regulatory air quality standards.

A known technology for control of exhaust gas pollutants from bothstationary and mobile sources is their catalyzed conversion into moreinnocuous chemical species. Conventional oxidation catalysts used inthis regard promote further burning of hydrocarbons and carbon monoxidein the exhaust gas. The normal operating temperature is 480° to 650° C.Oxidation catalysts in current use normally start oxidizing within twominutes after the start of a cold engine and will operate only when thecatalytic species is sufficiently heated to achieve an activationtemperature.

Known oxidation catalysts consist of platinum and mixtures of platinumand other noble metals, notably s palladium. These metals are depositedon alumina of high surface area. The alumina ceramic material istypically capable of withstanding very high temperatures. The ceramiccore has thousands of passages-about 240 per square inch. These passagespresent an enormous surface area for contact with the exhaust as itpasses through the catalytic converter. The ceramic passages are coatedwith the platinum and palladium metals. These metals provide thecatalysts.

When properly contained in the muffler-like shell of the catalyticconverter, the catalysts will reduce hydrocarbon and carbon monoxidepollutants by changing them into more harmless products of water vaporand carbon dioxide. Another common form of oxidization catalyst involvesa monolith in a honeycomb configuration to provide the necessary surfacearea and a top layer of the deposited catalytic metal species. Theselection of one or the other above catalytic configurations is dictatedby the kind of vehicle usage, as understood in the field.

However, conventional catalytic devices and catalytic species usedtherein have serious drawbacks in that they typically are susceptible topoisoning, i.e., deactivation resulting from chemical changes caused bythe combined effects of thermal conditions and contamination ascharacterized by a chemical reaction of a contaminant with the supportedcatalysts. For instance, the most notorious poison for vehicularcatalytic converters is the lead compound used as an anti-knockingagent. The poisoning of the catalysts by the contaminant, such as lead,is irreversible.

Moreover, many conventional catalysts also are susceptible toinhibition, or so-called reversible poisoning because of its temporaryeffect, due to exposure of the catalytic species to many common exhaustgas components such as carbon monoxide, nitrogen oxides or even somereduced sulfur compounds.

Compounding the poisoning problem encountered with many conventionalcatalysts used in treatment of exhaust gases is the demand for a moreversatile catalytic species having applicability to diverse areas ofexhaust gas treatment.

For instance, the federal and state regulatory attitude is everincreasingly stricter in imposing emission control standards covering aplethora of both commercial and private emission sources, e.g., coalburning plants and stoves, wood burning stoves, garbage incineration,used tire incineration, and not merely vehicle exhaust regulation.

Therefore, in an effort to meet current and perhaps even stricter futureenvironmental air quality objectives, many public and private concernshave urgently awaited any possible innovations in the catalytic exhaustcontrol field which might meet these standards.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide an emissioncontrol device containing a catalytic material capable of reducing thelevel of harmful pollutants contained in exhaust gases generated by thecombustion of fossil fuels, wood materials, rubber materials and thelike.

It is another object of the present invention to provide a catalyticmaterial which is not only capable of reducing the hydrocarbon, carbonmonoxide and carbon dioxide emissions from burnt fossil fuels, but whichalso can reduce NO_(x) emissions while concomitantly increasing theoxygen (O₂) content of the catalytically treated exhaust.

It is still another object of the present invention to provide animproved catalytic material which is highly resistant to poisoning fromexhaust contaminants and has versatility in treating a wide diversity ofcombustion gas material generated from, for example, solid and liquidfossil fuels, other carbonaceous materials such as wood and garbage, aswell as used tire rubber.

It is yet another object of the present invention to provide a catalyticmaterial useful for scrubbing of steam well gases.

Towards achieving the above and other objects of the present invention,this invention provides for a novel catalytic material obtained from avolcanic ash material located in northern Nevada, Washoe County, nearPyramid Lake.

The inventive material comprises predominantly, i.e., greater than 50%by weight, plagioclase feldspar. Plagioclase is a general name fortriclinic feldspars having anorthic or asymmetric crystal structure ofthree unequal long axes at oblique angles. Feldspar comprises themineral K₂ O,Al₂ O₃,6SiO₂.

Moreover, the predominant mineral component, plagioclase feldspar,belongs to the albite-anorthite series; in other words, the feldsparmaterial itself comprises albite and anorthite minerals. The albite(NaAlSi₃ O₈) and anorthite (CaAl₂ Si₂ O₈) minerals are completelycompatible and together form an isomorphous series ranging from the puresoda feldspar at the one end to the pure lime feldspar at the other endof the isomorphous series. There are isomorphous relations between thesetwo molecules and substantial identity of crystal structure. Forexample, the sodium and calcium atoms, on one hand, and the silica andaluminum atoms, on the other, may replace each other in the structure.

Additionally, the inventive material contains minor amounts of otherminerals, which, in sum, comprise less than 50% by weight of the totalweight of the inventive material. Among the minerals which mayconstitute the "minor components" of the, material and which have beenidentified are mica--KAl₂ Si₃ AlO₁₀ (OH)₂, kaolinite--H₄ Al₂ Si₂ O₉ or2H₂ O.Al₂ O₃.2Si₂ and serpentine--H₄ MgSi₂ O₉ or 3MgO.2SiO₂.2H₂ O. Theseminerals are considered to constitute the bulk of the minor components,but the material obviously may contain a variety of other impurities,i.e., small amounts of other minerals and trace amounts of variousmetals and other elements. In its native state, the material alsocontains magnetite (FeO.Fe₂ O₃).

While it has been discovered that the inventive material of the presentinvention can exhibit the catalytic effect in its native state, it hasfurther been discovered that the catalytic effect can be enhanced whenthe inventive material is subjected to a magnetic separation treatmentto remove magnetite (Fe₃ O₄ or FeO.Fe₂ O₃).

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe better understood from the following description as specificembodiments when read in connection with accompanying drawings.

Also, while the precepts of the present invention are presented in thecontext of an emission control device inserted into the output of anexhaust manifold of an internal combustion engine, it is to beunderstood that the inventive material and principles of its usedescribed herein are adaptable to many other types of combustion gastreatment units.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 represents a perspective view of an emission control devicecontaining the catalytic material of the present invention when insertedinto the output manifold of an internal combustion engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present invention, a catalytic material is used which is avolcanic ash obtained from an unusual mineral formation located innorthern Nevada, Washoe County, near Pyramid Lake.

While the igneous raw mineral used in the present invention is availablein different forms, two exemplary types of the material include thefollowing: (1) a mineral substance which is light beige in color andresembles a sandstone type of material or texture, and (2) a mineralsubstance which is black in color and resembles a basalt type ofmaterial.

Based on expert interpretations of X-ray studies and other elementalanalyses performed on the inventive material, both of theabove-described strains of the inventive material are principallyconstituted by plagioclase feldspar and possess a complex morphology andesoteric composition.

The predominant mineral component, plagioclase feldspar, is consideredto belong to the albite-anorthite series. The albite (NaAlSi₃ O₈) andanorthite (CaAl₂ Si₂ O₈) minerals are completely compatible in terms oftheir crystal structure, and together form an isomorphous series rangingfrom the pure soda feldspar at the one end to the pure lime feldspar atthe other end of the series. There are isomorphous relations betweenthese two molecules and substantial identity of crystal structure. Thesodium and calcium atoms, on one hand, and the silica and aluminumatoms, on the other, may replace each other in the structure.

Also, as noted above, other minerals may be present in the material inamounts of up to (in sum total) 50% by weight, including, but notnecessarily limited to, minor amounts of mica--KAl₂ Si₃ AlO₁₀ (OH)₂,kaolinite--H₄ Al₂ Si₂ O₉ of 2H₂ O.Al₂ O₃.2Si₂ and serpentine --H₄ MgSi₂O₉ or 3MgO.2SiO₂.2H₂ O. However, as noted above, a variety of impurities(other minerals, trace amounts of metals and other elements) are alsopresent, including magnetite.

ICP (Inductively Coupled Plasma) and AA (Atomic Absorption) analyseswere performed on the inventive material under the following protocol.The inventive material, as obtained from the source location describedherein, was ground and homogenized by means of a disk disintegrator inorder to obtain fraction of less than 100 mesh. Certain samples from theground material were subjected to magnetic separation (i.e., removal ofmagnetite) and then treatment at temperatures of 500° C. (932° F.) or750° C. (1382° F.) for two hours. The testing samples were numbered asfollows:

1. Original inventive material (clumps removed by mechanical grinding).

2. Inventive material after magnetic separation.

3. Magnetic fraction isolated from the original inventive material.

4. Inventive material after magnetic separation and after treatment at500° C.

5. Inventive material after magnetic separation and treatment at 750° C.

Samples 1, 2, and 3 were then digested in acids using the followingprocedure:

1 gram of a sample was placed in teflon beaker and added 15 ml nitricacid (HNO₃), 10 ml percloric acid (HClO) and 2 ml hydrofluoric acid(HF). That beaker was covered with teflon lid and placed on a 250° F.hotplate for 11/2 hours. Then the cover was removed and mixtures wereevaporated at 300° F. for 4 hours. The residue in the beaker was cooledand added 5 ml HNO₃ and 20 ml distilled water. The mixture was boiledfor 5 minutes and diluted to 50 ml in volumetric flask with distilledwater. That solution was analyzed for metal (but not Si/silica content -see below) content by means of Inductively Coupled Plasma (ICP) usingPerkin-Elmer Plasma II Emiston Spectrometer and by means of AtomicAbsorption Spectrometer using Perkin-Elmer AAS-3100. The results fromthese analyses are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    SAMPLE                                                                        NUMBER                                                                              `ICP` AND `AA` ANALYSIS OF MATERIAL IN PPM                              __________________________________________________________________________          Zn Cd                                                                              Pb Cu Co Ni Fe  Mn  Y Mg Co                                        __________________________________________________________________________    1     60 10                                                                              30 10 0  0  21500                                                                             475 10                                                                              3715                                                                             14740                                     2     45 0 35 10 0  0  11000                                                                             340 10                                                                              3440                                                                             15565                                     3     840                                                                              40                                                                              80 40 45 0  507000                                                                            3875                                                                              20                                                                              375                                                                              11235                                     __________________________________________________________________________          Mo W B  Ba P  Nb TT  As  Cr                                                                              Sb Te                                        __________________________________________________________________________    1     0  10                                                                              40 1100                                                                             365                                                                              15 1325                                                                              10  0 10 15                                        2     0   0                                                                              35 1110                                                                             300                                                                              15 1325                                                                              10  0 0  20                                        3     0  20                                                                              35 210                                                                              3115                                                                             175                                                                              1300                                                                              40  30                                                                              50 105                                       __________________________________________________________________________          Bi Be                                                                              V  Zr       No  K        Al                                        __________________________________________________________________________    1     0  0 30 75       30300                                                                             26500    111740                                    2     0  0 10 75       30200                                                                             26100    105220                                    3     10 10                                                                              845                                                                              40       4010                                                                              2800     20460                                     __________________________________________________________________________

To determine the SiO₂ content from samples 1, 2 and 3, the samples werealso subjected to high pressure digestion in hydrofluoric acid in orderto dissolve the materials. The samples were then analyzed as above, andSiO₂ content was found to be 66.3 wt% for sample 1, 67.1 wt% for sample2, and 11.7 wt% for the magnetic fraction, sample 3. Overall, theseelemental analyses of samples 1 and 2 confirm the mineral content of thematerial discussed above.

Also, after temperature treatment at 500° C. or 750° C. (samples 4 and5), the inventive material was subjected to X-ray diffraction analysis.The results revealed a material comprising mainly plagioclase feldsparand traces of mica. Kaolinite and serpentine s were also believed to bepresent but did not appear on the charts since these compounds releasetheir crystallization water when heated.

Also, ICP and DC plasma analyses on a sample of the inventive materialfurther detected the presence of the following elements, beyond thosealready noted in Table 1 above, in trace amounts in the material (on theorder of 0.5 ppm to 0.02% by weight for each element): Silver,molybdenum, nickel, tin, lithium, gallium, lanthanum, tantalum,strontium, zirconium, and sulfur. In addition, the presence of thefollowing oxides was confirmed: silica (SiO₂), titanium dioxide (TiO₂),alumina (Al₂ O₃), iron oxide as Fe₂ O₃ (magnetite), manganese oxide(MnO), magnesium oxide (MgO), calcium oxide (CaO), sodium oxide (Na₂ O),potassium oxide (K₂ O), and phosphorous oxide (P₂ O₅).

Another aspect of the present invention is the discovery that theinventive material can be used as a catalyst in at least two differentstates. For instance, the inventive material can be used in its nativestate or, alternatively, the inventive material can be subjected toconventional foundry furnace processing at approximately 2500° F. toform a solid metal alloy variation of the inventive material.

In either variation, the inventive material can be subjected to magneticseparation treatment to remove magnetite, in the main, before use of thematerial as a catalyst in its native state or after the foundrytreatment. The magnetic separation treatment can be performed with aconventional ferromagnetic device or a conventional electromagneticdevice.

Therefore, while the invention is illustrated in greater detail hereinwith exemplary usage of the inventive material in its native state(preferably after agglomerated clumps are mechanically eliminated), itis understood that the present invention also encompasses the usage ofthe solid metal alloy version of the inventive material.

As another important aspect of the present invention, it has beendetermined that the inventive material of the present invention exhibitsits unexpected catalytic effect after being activated by heating to andmaintaining a temperature of approximately 850° F. or higher. However,this activation can be accomplished in-situ (in the automobile exhaustsystem) if the activating temperature of approximately 850° F. or higheris experienced by the emission control device as installed in the hotexhaust system.

On the other hand, if the exhaust system does not operate continually atthe activating temperature, then external heating sources, described ingreater detail hereinafter, may be used to provide the supplementalheating needed for activating the inventive material in the installedemission control device.

Unlike conventional honeycomb systems with platinum or palladium, themineralsubstance of the present invention will not clog up a honeycombsurface so as to necessitate replacements of the converter after a givenperiod of usage.

Also, and significantly, the inventive material or alloy substance ofthe present invention does not become deactivated or poisoned due toexposure to exhaust contaminates such as lead Therefore, the inventivematerial of the present invention is particularly useful for catalytictreatment of combusted leaded gasoline.

Moreover, the nature of the inventive compound or alloy compound of thepresent invention allows for applications to be cast, shaped, and/orfabricated into any desired configuration commensurate with the specificusage, such as car exhaust manifolds, and coal burning smokestacks andstoves requiring customized designs of the emission control device.

Additionally, it has been determined that the catalytic effect of theinventive material of the present invention is demonstrated in itsnative state, but this catalytic effect also can be significantlyenhanced after subjecting the original inventive material to a magneticseparation treatment. During the magnetic separation, the black fractionof the material is taken out which mainly comprises magnetite (Fe₃ O₄ orFeO.Fe₂ O₃). The magnetic fraction may also contain hydroxylapatite--Ca₅(PO₄)₃ OH.

When heated to 220° C. in oxygen, the inventive material remaining aftermagnetical separation changes in color to red Fe₂ O₃ without, however,any noticeable change in magnetism or the X-ray structure pattern, butwhen heated further to 550° C., all magnetism disappears. This loss ofmagnetism is believed to be associated with the color change observed inthe material during heating at the higher operating temperatures of 850°F. or higher.

While the inventive material of the present invention has many anddiverse possible applications, as suggested above, the use of theinventive material in an emission control device inserted in an exhaustmanifold output of an internal combustion engine is described in detailbelow for illustration purposes.

It has been discovered that an emission control device containing theinventive material of the present invention, when inserted into theexhaust system of a gasoline engine, will reduce the harmful emissionsof hydrocarbons, carbon monoxide and carbon dioxide by as much as 72% ofthe original content. Moreover, a reduction in the NO emissions isobserved concomitant with an increase in the emission of oxygen (O₂).

An illustrative depiction of the emission control device, as to beinstalled, is provided in FIG. 1. The elements depicted in FIG. 1 aredescribed below by reference to their assigned reference numerals.

1--tail pipe

2--Retaining ring

3--Seal

4--Self-locking nut

5--Clamp

6--Clamp belt

7--Silencer

8--Seal

9--Air inlet hose

10--Hose clip

11--Grommet

12--Connecting pipe

13--Gasket-pre-heater pipe (left)

14--Gasket-pre-heater pipe (right)

15--Gasket-exhaust pipe flange

16--Self-locking nut

17--Clamp

18--Heat exchanger

19--Bolt

20--Pin

21--Circlip

22--Heater cable link

23--Pin

24--Clamp washer

25--Heater flap lever (left)

26--Lever return spring (left)

27--Emission Control Device (E.C.D.)

The E.C.D. insert device 27 can be installed without the need formodification of the existing engine exhaust system. However, atmosphericair must be prevented from entering the manifold before the emissioncontrol device (E.C.D.). All connections must be sealed.

In order to achieve satisfactory operating efficiency of the E.C.D., theoptimum exhaust gas temperature is 850° F. or above. The temperature ismeasured at the base of the E.C.D. In cold engine starting, and in someengines when idling, the exhaust gas temperature is below 850° F., sowhen this occurs, an external thermostat-controlled preheater device(not depicted) is attached to the E.C.D. For instance, a heating wire(not depicted) is connected between the E.C.D. and a remote thermostat.The heating wire is preferably coated with inventive material using thesame type of paste employed in the E.C.D. and described hereinafter.

When using the preheater device, the E.C.D. begins to function withinone minute of a cold engine start. When the engine exhaust gastemperature rises to 850° F. the thermostat automatically turns off thepreheater and remains off unless the temperature falls below 850° F. Thepreheater can be powered by the existing vehicle battery and produces anamperage load approximately equal to a factory installed cigarettelighter. Activation of the preheater can be accomplished through theaccessory section of the ignition switch, so there is no battery currentdrain until the engine is started.

In the event E.P.A. regulations change to include cold engine starting,the E.C.D. can simply be controlled in a similar manner as adapted fromknown diesel engine preheaters for cold starting in current use.

As depicted in FIG. 1, the E.C.D. 27 is tubular in construction or,alternatively, of strip construction, and is mounted in a standardexhaust manifold to tail pipe flange. The tube section O.D. isdetermined by the I.D. of the exhaust manifold opening. Since themanifold port inside diameter is greater than the exhaust tail pipeI.D., the device may be inserted into the manifold without creatingexhaust back pressure.

The tube portion of the E.C.D. may be steel or steel alloy or a ceramic.The tube is attached to a standard exhaust pipe flange that boltsdirectly to the manifold. When the device is installed, the tube portioninserts into the manifold and the flange is sandwiched between themanifold and the exhaust tail pipe flange. The preheater electricalconductor protrudes through, but is insulated from the flange, andconnects directly to the thermostat.

Since the tube acts only as a carrier for the reactive coating, thecomposition of the tube carrier need only be selected with theconstraint that it is able to withstand the high temperature of theexhaust gas and the operating temperature of the E.C.D. In this regard,high temperature ceramic tubes are useful.

The active ingredient of the E.C.D. is a coating containing theinventive material as applied to the tube surface portions, both insideand outside, and also onto the preheater wire, if needed.

In order to provide this coating, the inventive material described aboveis first dry pulverized to powder size of no less than 40 mesh butsufficient to eliminate clumps. Then the inventive mineral material isapplied to the surface of the E.C.D. tube in a dispersed state in a hightemperature ceramic paste, then cured in an oven at elevatedtemperature. A representative ceramic paste is Zirconia Ultra Hi-TempCeramic supplied by CoTronics Corp. This paste can withstand heat of upto 4000° F.

Installation of the Emission Control Device can be accomplished by theprocedure of placing the vehicle on a hoist, removing themanifold-to-tail pipe bolts, lowering of the pipe approximately threeinches. Then, tube portion of the E.C.D. is inserted into the exhaustmanifold, then the flange is aligned with the manifold bolt, and thenthe tail pipe is replaced and the manifold bolt tightened.

On 2-4 & 6 cylinder engines having one exhaust manifold, one E.C.D.typically is used. On a V6 and V8 engines, the E.C.D. is inserted ineach manifold.

The basic shape of the device is maintained for all engines, but thesize is determined by the cubic inch displacement of the engine.Approximately five flanges and tube sizes will fit U.S. vehicles andsome foreign vehicles. The emission control device of the presentinvention can be used alone as a catalytic converter for the exhaustsystem of a gasoline engine or, more desirably, can be used to augmentexisting exhaust systems.

When installed in older vehicles and any four cycle gasoline engines,the emission control device of the present invention acts a catalyticconverter transforming the engine into a clean emission engine whichmeets current state emission standards. Also, while automotivemanufacturers have different exhaust configurations, the emissioncontrol device of the present invention can be adapted to physically fitthe different engine exhaust pipes in ready fashion. Nonetheless, theoperating efficiency of the emission control device of the presentinvention remains the same.

As can be appreciated from the descriptions provided herein, thecatalytic device and inventive material of the present inventionprovides an improved catalytic material which is highly resistant topoisoning from exhaust contaminants and has versatility in treating awide diversity of combustion gas material generated from, for example,solid (e.g. coal) and liquid fossil fuels, other carbonaceous materialssuch as wood and garbage, as well as used tire rubber.

While the invention has been described in detail and with reference to aspecific embodiment thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. An emission control device comprising a substratesupporting a, catalytic material comprising plagioclase feldspar in anamount greater than 50 wt%, said feldspar mainly comprising albite andanorthite minerals, and said material containing magnetite.
 2. Theemission control device as claimed in claim 1, wherein said materialfurther comprises a minor proportion of mica, kaolinite and serpentinein a total amount of less than 50 wt%.
 3. The emission control device asclaimed in claim 1, wherein said substrate carries the catalyticmaterial in the form of a cured ceramic adhesive having the materialuniformly dispersed therein, said adhesive capable of withstandingtemperatures of 850° F. or higher.
 4. An emission control devicecomprising a substrate supporting a catalytic material comprisingplagioclase feldspar in an amount greater than 50 wt%, said feldsparmainly comprising albite and anorthite minerals, from which magnetitehas been removed.
 5. The emission control device as claimed in claim 4,wherein said material further comprises a minor proportion of mica,kaolinite and serpentine in a total amount of less than 50 wt%.
 6. Theemission control device as claimed in claim 4, wherein said substratecarries the catalytic material in the form of a cured ceramic adhesivehaving the material uniformly dispersed therein, said adhesive capableof withstanding temperatures of 850° F. or higher.
 7. A catalyticmaterial comprising plagioclase feldspar in an amount greater than 50wt%, said feldspar mainly comprising albeit and anorthite minerals, fromwhich magnetite has been removed.
 8. A catalytic material as claimed inclaim 7, further comprising a minor proportion of mica, kaolinite andserpentine in a total-amount of less than 50 wt%.